Rollup merge of #108482 - Ezrashaw:force-error-docs, r=GuillaumeGomez

statically guarantee that current error codes are documented

Closes #61137 (that's right!)

Pretty simple refactor (often just a change from `Result<Option<&str>>` to `Result<&str>`)

r? `@GuillaumeGomez` (could you specially look at 53044158eff0d64673a6100f701c57b484232aca? I believe you wrote that in the first place, just want to make sure you're happy with the change)

3 files changed, 20 insertions, 63 deletions

diff --git a/src/tools/error_index_generator/Cargo.toml b/src/tools/error_index_generator/Cargo.toml
index f4dac6e947e..76c2e330b21 100644
--- a/src/tools/error_index_generator/Cargo.toml
+++ b/src/tools/error_index_generator/Cargo.toml
@@ -5,6 +5,7 @@ edition = "2021"
 
 [dependencies]
 mdbook = { version = "0.4", default-features = false, features = ["search"] }
+rustc_error_codes = { version = "0.0.0", path = "../../../compiler/rustc_error_codes" }
 
 [[bin]]
 name = "error_index_generator"
diff --git a/src/tools/error_index_generator/main.rs b/src/tools/error_index_generator/main.rs
index 373196b6642..f984275b164 100644
--- a/src/tools/error_index_generator/main.rs
+++ b/src/tools/error_index_generator/main.rs
@@ -2,9 +2,6 @@
 
 extern crate rustc_driver;
 
-// We use the function we generate from `register_diagnostics!`.
-use crate::error_codes::error_codes;
-
 use std::env;
 use std::error::Error;
 use std::fs::{self, File};
@@ -17,22 +14,6 @@ use std::str::FromStr;
 use mdbook::book::{parse_summary, BookItem, Chapter};
 use mdbook::{Config, MDBook};
 
-macro_rules! register_diagnostics {
-    ($($error_code:ident: $message:expr,)+ ; $($undocumented:ident,)* ) => {
-        pub fn error_codes() -> Vec<(&'static str, Option<&'static str>)> {
-            let mut errors: Vec<(&str, Option<&str>)> = vec![
-                $((stringify!($error_code), Some($message)),)+
-                $((stringify!($undocumented), None),)*
-            ];
-            errors.sort();
-            errors
-        }
-    }
-}
-
-#[path = "../../../compiler/rustc_error_codes/src/error_codes.rs"]
-mod error_codes;
-
 enum OutputFormat {
     HTML,
     Markdown,
@@ -55,11 +36,8 @@ fn render_markdown(output_path: &Path) -> Result<(), Box<dyn Error>> {
 
     write!(output_file, "# Rust Compiler Error Index\n")?;
 
-    for (err_code, description) in error_codes().iter() {
-        match description {
-            Some(ref desc) => write!(output_file, "## {}\n{}\n", err_code, desc)?,
-            None => {}
-        }
+    for (err_code, description) in rustc_error_codes::DIAGNOSTICS.iter() {
+        write!(output_file, "## {}\n{}\n", err_code, description)?
     }
 
     Ok(())
@@ -105,27 +83,23 @@ This page lists all the error codes emitted by the Rust compiler.
 "
     );
 
-    let err_codes = error_codes();
+    let err_codes = rustc_error_codes::DIAGNOSTICS;
     let mut chapters = Vec::with_capacity(err_codes.len());
 
     for (err_code, explanation) in err_codes.iter() {
-        if let Some(explanation) = explanation {
-            introduction.push_str(&format!(" * [{0}](./{0}.html)\n", err_code));
-
-            let content = add_rust_attribute_on_codeblock(explanation);
-            chapters.push(BookItem::Chapter(Chapter {
-                name: err_code.to_string(),
-                content: format!("# Error code {}\n\n{}\n", err_code, content),
-                number: None,
-                sub_items: Vec::new(),
-                // We generate it into the `error_codes` folder.
-                path: Some(PathBuf::from(&format!("{}.html", err_code))),
-                source_path: None,
-                parent_names: Vec::new(),
-            }));
-        } else {
-            introduction.push_str(&format!(" * {}\n", err_code));
-        }
+        introduction.push_str(&format!(" * [{0}](./{0}.html)\n", err_code));
+
+        let content = add_rust_attribute_on_codeblock(explanation);
+        chapters.push(BookItem::Chapter(Chapter {
+            name: err_code.to_string(),
+            content: format!("# Error code {}\n\n{}\n", err_code, content),
+            number: None,
+            sub_items: Vec::new(),
+            // We generate it into the `error_codes` folder.
+            path: Some(PathBuf::from(&format!("{}.html", err_code))),
+            source_path: None,
+            parent_names: Vec::new(),
+        }));
     }
 
     let mut config = Config::from_str(include_str!("book_config.toml"))?;
diff --git a/src/tools/tidy/src/error_codes.rs b/src/tools/tidy/src/error_codes.rs
index 8c904e8d712..c60caa0d49c 100644
--- a/src/tools/tidy/src/error_codes.rs
+++ b/src/tools/tidy/src/error_codes.rs
@@ -45,7 +45,7 @@ pub fn check(root_path: &Path, search_paths: &[&Path], verbose: bool, bad: &mut
     let mut errors = Vec::new();
 
     // Stage 1: create list
-    let error_codes = extract_error_codes(root_path, &mut errors, verbose);
+    let error_codes = extract_error_codes(root_path, &mut errors);
     println!("Found {} error codes", error_codes.len());
     println!("Highest error code: `{}`", error_codes.iter().max().unwrap());
 
@@ -65,18 +65,17 @@ pub fn check(root_path: &Path, search_paths: &[&Path], verbose: bool, bad: &mut
 }
 
 /// Stage 1: Parses a list of error codes from `error_codes.rs`.
-fn extract_error_codes(root_path: &Path, errors: &mut Vec<String>, verbose: bool) -> Vec<String> {
+fn extract_error_codes(root_path: &Path, errors: &mut Vec<String>) -> Vec<String> {
     let path = root_path.join(Path::new(ERROR_CODES_PATH));
     let file =
         fs::read_to_string(&path).unwrap_or_else(|e| panic!("failed to read `{path:?}`: {e}"));
 
     let mut error_codes = Vec::new();
-    let mut reached_undocumented_codes = false;
 
     for line in file.lines() {
         let line = line.trim();
 
-        if !reached_undocumented_codes && line.starts_with('E') {
+        if line.starts_with('E') {
             let split_line = line.split_once(':');
 
             // Extract the error code from the line, emitting a fatal error if it is not in a correct format.
@@ -111,23 +110,6 @@ fn extract_error_codes(root_path: &Path, errors: &mut Vec<String>, verbose: bool
             }
 
             error_codes.push(err_code);
-        } else if reached_undocumented_codes && line.starts_with('E') {
-            let err_code = match line.split_once(',') {
-                None => line,
-                Some((err_code, _)) => err_code,
-            }
-            .to_string();
-
-            verbose_print!(verbose, "warning: Error code `{}` is undocumented.", err_code);
-
-            if error_codes.contains(&err_code) {
-                errors.push(format!("Found duplicate error code: `{}`", err_code));
-            }
-
-            error_codes.push(err_code);
-        } else if line == ";" {
-            // Once we reach the undocumented error codes, adapt to different syntax.
-            reached_undocumented_codes = true;
         }
     }